Filter elements of pleated media are often arranged in a tubular construction. By the word “tubular”, it is meant a closed loop, which can be round, non-round, oval, elliptical, racetrack shaped, etc. The filter elements can be used in a variety of applications such as cleaning the air intake for compressors or filtering the air in dust collectors. In many cases, the fluid to be filtered flows from the exterior, through the pleats, and into the open interior volume of the tubular construction. In many situations, it is desirable to support the pleated media from within the interior volume of the filter element in order to prevent the pleats from collapsing against themselves in the interior volume. When the tubular construction is oval, elliptical, or racetrack shaped, the problem with having the pleats collapse against themselves is even more of an issue because of the geometry of the cross-sectional shape of the media construction.
One typical approach to supporting the filter media within the interior of the filter includes using an inner filter liner. The inner filter liner is often made from metal and is porous to allow fluid flow there through. There have been uses in the prior art of non-metal inner liners, as well.
When used in dust collectors, filter elements can be periodically cleaned by back flushing the elements through the use of a pulse of compressed gas or air. The durability of the filter elements is important for long filter life. In prior art elements that have an inner liner that extends an entire length between the end caps, the pulse cleaning process can cause stress as the filter media tries to bow outwardly. This may cause a failure point by tearing the media where it is connected to the end caps, or by causing damage by the inner liner to the end caps, leading to premature failure, leak paths, or other problems.
Improvements in filter elements and media support are desirable.